1. CIS Case History NACE Eastern Area Conference
Jeffrey L. Didas Colonial Pipeline Company 2607 Willard Road Richmond, VA

2. INTRODUCTION
Close - Interval Potential Surveys (CIS or CIPS) are performed for many reasons. The primary purpose of a CIS is to ensure that a pipeline is cathodically protected in its entirety.
CIS is also used as a method to verify pipeline integrity, evaluate coating condition and follow up on areas after pipeline rehabilitation.

3. CIS GENERAL DISCUSSION
Close - Interval Potential Surveys have been utilized for decades. In the early years it involved hand reels or multiple hand reels of wire stretched out between test points and bulky analog meters which remained stationary at the test points, with a moving reference electrode(s) traveling along and over the pipeline.

4. CIS GENERAL DISCUSSION
Today’s data loggers and wire dispensers provide a light – weight, accurate and fairly simple method of recording, analyzing and displaying CIS data.

5. CIS GENERAL DISCUSSION
Motorized or power reels with several miles of survey wire supplemented the hand reels and improved the process, which still used a stationary analog meter and moving the electrodes. During the 1970’s digital meters, data logging hardware, small diameter survey wire and wire dispensers evolved into an over the line surveyor having all the survey equipment with the surveyor.

6. CIS GENERAL DISCUSSION
Today’s data loggers and wire dispensers provide a light – weight, accurate and fairly simple method of recording, analyzing and displaying CIS data.
With today’s computer technology and what is known about the technology, the survey interval has become fairly standard at 1 m (2.5 feet).

7. CIS ISSUES GENERAL DISCUSSION
CIS specification – one is required whether for internal or external use.
CIS contractor or in house personnel – proper training, experience and OQ’s are required.
CIS data quality and availability – data must be per the specification, be usable and repeatable and available in a timely manner upon completion of the CIS.

8. CIS ISSUES - GENERAL DISCUSSION
Pipeline operators have implemented Integrity Management Plans – (IMP’s) which gives them a long term plan to use for evaluating the pipelines integrity and implementing a rehabilitation plan
These evaluations use a combination of internal inspections using ILI, external inspections using CIS and DCVG, then wrapping all these programs together using External Corrosion Direct Assessment (ECDA), Internal Corrosion Direct Assessment (ICDA) and Stress Corrosion Direct Assessment (SCCDA).

9. CIS ISSUES and ANSWERS - GENERAL DISCUSSION
When ILI is not practical for the IMP, CIS becomes extremely valuable as the primary component for performing the evaluations.
The CIS will determine the areas not meeting a cathodic protection (CP) criterion.
The areas not meeting these criteria will be further evaluated using an above ground coating evaluation survey and normally a depolarized potential survey.

10. CIS – GPS Survey In Progress
Typical Cross Country Pipeline ROW

11. CIS – GPS Survey In Progress
Where’s the pipe? They appear to be lost in the field.

12. CIS Technical Issues Locating Pipeline
Interrupter Accuracy and Quality
Interruption Cycle
Reference Electrode Calibration
Crew Quality
ROW Conditions
Level of CP and Coating Quality

13. Typical CIS Data Plot

14. Data Issues Repeatability of Data
Ability to locate Deficiencies – GPS Accuracy
Data integration into database

15. CIS DATA ANALYSIS
The results of the coating evaluation testing will drive the rehabilitation program and allow selection of the rehabilitation method
Which method or combination of methods is determined by the corrosion engineer analyzing all the data, performing current require testing, performing coating conductance and / or quality surveys, running design calculations for CP systems and determining the most cost effective methods.

16. CIS Case History 32” Products Pipeline Installed 1961
Asphalt Enamel Coating
Recently had a CP Upgrade Performed
ILI has had Multiple Runs – no corrosion issues
ON/OFF survey with GPS and depth of cover survey was run
Areas not meeting -850 ON were addressed

17. Results 30 anomaly locations were selected for recoat
45 anomaly locations were selected for new CP or upgrading existing CP
100% compliance was achieved after rehabilitation was completed and follow up survey run

18. Location Selected for Recoating

19. Area Being Excavated

20. Problem Area Identified and Coating Being Removed

21. Entire Area That was Examined

22. Area Kept Growing

23. Some Coating was Actually Sticking to the Pipe

24. Found a Problem at the Area of Investigation

25. Problem Remediated

26. Abrasive Blasting in Progress

27. Recoating in Progress

28. Coating Inspection

29. Coating Inspection

30. Recoating Complete

31. Follow Up Survey in Progress

32. Summary and Conclusions
Close Interval Potential Survey is a proven tool to use to evaluate pipelines to ensure it is cathodically protected or to locate areas that are not protected.
Using CIS to determine areas of your pipeline that require coating rehabilitation does work and works very well.

33. Summary and Conclusions
CIS data alone should not be used in locating areas that require coating rehabilitation, but a combination of CIS data, ILI data (when available), above ground coating surveys and competent corrosion engineering analysis of the entire rehabilitation project is required.